Velocity

Which describes the average velocity of an object?

(x_2 - x_1) / (t_2 - t_1)

What is the displacement of the object? x_1 = 4 x_2 = 2

-2

A particle starts at the origin and moves in a straight line. After 1.2 seconds, it is 9.4 meters from the origin. At this point the particle reverses direction. After 3.1 seconds in total, the particle is at -6.23 meters. What is the average velocity of the particle over the 3.1 s?

-2.0 m/s

A particle is displaced -30m in a straight line in 0.5s. What is its average velocity within that interval?

-60 m/s

If a person runs from position x1 to x2 in 2 s, what is the velocity of the person? x_1 = -3 x_2 = -1

1 m/s

A cyclist in a long distance race travels a total of 4,810 km in 10 days, 6 hours, and 12 minutes. The direct distance between the start and end points of the race is 2,808 km. What was the cyclist's average velocity?

11.4 km/h

What is the displacement of the object? x_1 = 1 x_2 = 4

3

A particle starts at the origin and is deflected by another particle with a like charge. In 0.5s the first particle has moved 30m in a positive direction. What is its displacement?

30m

A person holding a checkered flag high in the air stands 4 m in front of a line of race cars. When the flag is dropped, the race begins. The fastest car reaches a point 100 m beyond the flag in 1.92 s. What is the average velocity of the car in meters per second (m/s) during this time interval?

54.2 m/s

The Johnsons travel from their home to a relative's home in 2.45 h. Measured on their car's odometer they traveled 223 km. The straight-line distance between the two homes is 197 km. What was the average velocity during the trip?

80.4 km/h

You and a friend stand 10 m apart. Your dog, initially midway between you, runs in a straight line toward your friend. Each of you independently defines a coordinate system (position of origin and positive direction for the coordinate x) and calculates the dog's average x-component of velocity. (Remember in this context, when we say "velocity," we really mean "x-component of velocity.") What can you say with certainty about the average velocity?

both of you can obtain a negative velocity (Either person can choose either axis, so either person can obtain either sign for velocity)

What is the definition of average velocity?

the change in x divided by the time interval in which that change occurs

Which describes the displacement of an object?

the change in x, or position

Which can describe the displacement of an object?

x_2 - x_1